1. Field of the Invention
The present invention relates, generally, to a passive flexion chair for physical therapy. More particularly, the present invention relates to an apparatus for imparting passive motion flexion to a lower limb of a person, such as, for example, the knee of a person recovering from an injury. Such apparatus are generally known in the relevant art as continuous passive motion ("CPM") systems.
When a joint, such as one's knee, is immobilized due to an injury, disease, etc., the soft tissues at the joint begin to contract. As a consequence of such contraction, motion of the joint is limited both by actual physical restraint, as well as by psychological restraints wherein a patient either experiences pain as a result of movement of the joint or, at a minimum, fears the pain which might result from stretches of the soft tissues of the joint beyond a certain point. However, in order to return the joint to its normal range of mobility, the soft tissues, over time, must be stretched in order to increase the range of motion of the joint.
Stretching of the soft tissues of the joint is best carried out by passive manipulation of the joint, since the muscles that operate the joint are in a weakened condition as a result of the injury. During the manipulation of the joint, pain will result as scar tissue and adhesions are broken off. The pain encountered during passive manipulation of the joint must be strictly controlled and always held below the patient's allowable tolerance for pain. If a patient's allowable tolerance for pain is exceeded, new and painful adhesions could be formed and result in a regression in the patient's joint condition.
Operation in a comfort zone within the patient's allowable tolerance for pain is also important since stretching of the soft tissues is facilitated as the patient relaxes and tense muscles are overcome by weariness. A sitting position facilitates the relaxation of muscles surrounding the injured area.
To continually assure operation in the comfort zone, the stretching necessarily must be carried out gradually and over an extended period of time.
Because of the requirement that the stretching therapy must take place over an extended period of time, uniform and continuous mechanical therapy is both practical and required, as opposed to relying solely upon manual therapy by a trained physical therapist. The reasons for this include the fact that a physical therapist will not have the stamina to continue the treatment in a uniform and consistent manner over an extended period of time. The mechanical method may allow for a more accurate measurement of progress. This is true during individual therapeutic sessions, as well as over time from session-to-session. By contrast, the passive flexion chair of the present invention, as will be described in detail hereinafter, will ensure a continuous and uniform treatment over an extended period of time, as well as allowing the patient to continuously adjust and re-adjust the degree of stretching.
Additionally, the monetary cost of contracting a professional physical therapist for constant and total involvement in the healing process, over an extended period of time, will quickly become prohibitive. By contrast, the passive flexion chair of the present invention can manipulate the joint to be treated over an extended period of time without the physical therapist being in attendance, thereby considerably reducing the cost of treatment.
Further, a skilled therapist must generally rely a upon trial-and-error approach, through his or her sense of feel, in order to establish the range of motion of the joint that was attained in the previous treatment, so as to use it as a starting point for the next treatment, to establish a specific desired angle through which the joint is able to be reciprocated during treatment, and to establish a specific desired force to be applied during treatment for the next desired range of motion. The passive flexion chair ("PFC") provides a consistent and accurate method for measurement in tracking the progress attained during previous treatments.
Overall, the present invention, as to be described below, provides for an accurate control of the angle through which the joint is reciprocated during passive manipulation and of the amount of force applied during the manipulation.
The apparatus of the present invention further provides a passive knee flexion device which is very easy to utilize by the patient in terms of its controls and set up and, further, in terms of mounting and dismounting from the apparatus by the patient.
Other applications and benefits of the present invention will become readily apparent as the apparatus of the present invention is described in further detail below.